1. Field of the Invention
The present invention relates generally to a radio receiver having a squelch circuit, and more particularly pertains to a new and improved circuit for a rapid channel skip system for a radio receiver wherein any predetermined frequencies also known as channels having a plurality of channels can be skipped, inhibited, bypassed, looked around, etc., by inhibiting any predetermined channels of a plurality of channels in a first manual or automatic scanning cycle which are subsequently skipped in second and subsequent scanning cycles.
2. Description of the Prior Art
In the field of scanning radio receivers, it has been a general practice to employ a plurality of switches for an equal plurality of channels to lock out, disable, etc., any channels of predetermined frequencies such as a police frequency, fire frequency, sheriff frequency, highway patrol frequency, etc., and a single clock oscillator to control the scanning frequency of all the channels.
The most common type of lockout, disable, etc., switches employed are slide or pushbutton switches which are slid, or pushed in or out to an on position to lockout, disable, etc., any predetermined channels. A separate slide or pushbutton switch is employed for each separate channel to lockout each channel. These types of switches or any type of a plurality of switches in general are time consuming to utilize in addition to presenting certain maintenance problems to keep the switches in an operational condition.
A typical scanning radio receiver using a plurality of lockout switches, one switch per channel, is described in a patent issued to Boone et al, U.S. Pat. No. 3,883,808, issued on May 13, 1975, entitled "Radio".
A typical scanning radio receiver using a multi speed clock is described in a patent issued to Koch, U.S. Pat. No. 3,714,585, issued on Jan. 30, 1973, entitled "Scanning Radio Having Rapid Channel Skipping Capability." The frequency of the multi speed clock is controlled by each individual channel skip switch for each respective channel to skip locked out channels at a fast rate. When a channel is skipped, the channel visual indication device glows dimly.
This invention eliminates the use of a separate switch for each of the plurality of channels by providing a single channel skipping, inhibiting, bypass, look around, channel choice, etc., switch for all of the channels used in conjunction with a memory for each channel which stores status information as to whether the channel is electronically turned "on" or "off."
Also, this invention uses two separate oscillators, a clock oscillator at a scanning frequency to scan channels to be received and a skip oscillator at a skipping frequency to skip inhibited frequencies by advancing the counter to the next channel in conjunction with a single channel skipping switch. The advancement is at a frequency such that the crystal is unable to stabilize into oscillation and the visual indicating device will not light.